Automotive vehicle



w. F. ROCKWELL ETAL Sept, 11, 1945.

' AUTOMOTIVE VEHICLE Filed March 23, 1944 6 Sheets-Sheet 1 1% h a/fer[Rod/98% Be er/y M Keeae p 1 1945. w. F. ROCKWELL Em 2.384.182

- AUTOMOTIVE VEHICLE Filed March 23, 1944 6 Sheets-Sheet 2 D I no 1 3 Iu x H l I 2 I S w R E O l I I, I

g x .E v r- 8 TI 13 v Q S v 0 1G .5 1': -S B Q t 0 k M Q a a Q) R 1 hawflfiocfimefl Beyer/y I1! fleese p 1945- w. F. ROCKWELL arm. 2,334,782-

AUTOMOTIVE VEHICLE Filed March 23, 1944 6 Sheets-Sheet 3 JMW W090 Sept.1945' w. F. ROCKWELL ETAL ,78

AUTOMOTIVE VEHICLE Filed March 23, 1944 6 Sheets-Sheet 5 Beyer/y nlfeese6 Sheets-Sheet 6 W. F.'ROCKWELL ETAL AUTOMOTIVE VEHICLE Filed March 23,1944 QVN QAN OWN Sept. 11, 1945,

Patented Sept. 11, 1945 AUTOMOTIVE VEHICLE Walter F. Rockwell, Detroit,Mich, and Beverly W. Kecse, Oshkosh, Wis, assignors to TheTlmken-Detroit A xle Company, Detroit, Mich a corporation of OhioApplication March 23, 1944, Serial No. 527,782

(Cl. l80-54L) 20 Claims.

This invention relates to improvements in automotive vehicles and hasparticular reference to a heavy duty automotive vehicle having a mainengine furnishing the power under most operatmg conditions and a boosteror auxiliary engine for furnishing supplementary power at times when thepower of the main engine is inadequate to maintain a desired vehiclespeed and is a continuation-impart of co-pending application Serial No.506,582, filed October 16, 1943 and is an improvement over co-pendingapplication Serial No. 3563M, filed September 10, 1949. C- pendingapplication Serial No. 432,520, filed Februarv 26, 1942, discloses aspecial development oi have been accentuated by the increased loadscarried and increased speeds permitted. For example, with manualoperation required to start the prior booster or auxiliary engines ofthe prior disclosures, the driver has had to divert his attention to thestarting of this engine at times when his attention is otherwise heavilyengaged in negotiating grades and curves and attempting to maintain thevehicle speed such that the booster engine may be smoothly coupled intothe available power. He has had to watch the smeol and the load on themain engine to determine when the use of the auxiliary or booster engineis necessary, has had to use extreme skill and additional physicaleiiort in shifting when the same general subject matter. thetransmissions oi? the two engines were con-- Various arrangements havebeen heretofore pied together by previous mechanical devices, andproposed providing a plurality of motors for drivhas experienceddifficulty in controlling the ining a vehicle having motors or like ordiiierent creased load on steep grades or at high speeds capacitiesoperating through the same drive with previous conventional bra-heequipment. lines and designed either for alternative or simul- It istherefore among the objects or" the pres tanecus operation withoutregard to the tractive entinvention to provide a heavy duty boosterenefiort that can he absorbed by the driving wheels. gine vehicle withimproved controls and brake Eluch vehicles have in general not beenpracequipment effective to relieve the driver of most deal because ofthe excessive tire and other wear or all or the excess burden overoperating a conan dvehicle maintenance expense, inefilciency oivolitional single engine vehicle of the same genoperation, dlfilculty ofcontrol on the part of the em]. class and to so pr r the loads 911.31%driver, and other practical disadvantages. The vehicle parts and tiresthat undue wear and only multiple motor road vehicles that have beenstrain will not occur. heretofore successful to our mowledge are of theA further object resides in the provision, in a type in which separatewheels or axles are driven an vehicle or the character indicated, of anovel arsimultaneously by individual motors in normal rangement of amain engine having a power outopersution put capacity based on thetraction capacity of The foregoing problems we have solved by prothemain drive axle or axles of the vehicle and violins main andboosterengines driving didersumc'lent to normally furnish all of thepower ent wheels through independent drive lines, confor propelling thevehicle, and a booster engine trolled through a novel controlarrangement and having a power output capacity based on the havingmaximum powers insumcient to slip the tractive capacity oi anothervehicle axle such as wheels driven thereby under normal road condiafront steer drive axle or trailer axle suppletions. In the preferredembodiments of our inmenting the power of the main engine. vention, thebooster engine is operative only so A somewhat more specific objectresides in the when the power of the main engine is insufiprovision ofservo controls for the starting, clent to maintain the desired vehicleor tractor clutching and shifting operations of the booster and trailerspeed under particular conditions. engine which operate smoothly andsubstantially Our invention has been found in long comparaautomaticallyand with which substantially no the road tests to have materialadvantages in additional skill, attention or physical effort on reducedrunning time, increased load carrying the part of the driver is requiredwhen both encapacity, improved fuel consumption and nongines areoperating than when only themain eninterference with other treflic onthe highways. gine is in operation.

In the earlier embodiments of our invention A further object resides inthe provision of an disclosed in said co-pending applications, whileimproved starting control for the booster engine providing variousimportant advantages over the arranged to give the driver a choicebetween fully prior arrangements, ithas been found that the automaticand manual starting of the booster encontrol arrangements used haveimposed addigine andto positively prevent the booster engine tionalburdens on the drivers or the vehicle which starter motor beingenergized while the booster engine is running.

. A stillfurther object resides in the provision of improved brakeequipment which will enable the driver to hold the increased loads onsteep grades without any material increase in physical short and withoutdamage to the brake equipment.

Other objects and advantages will be more particularly pointed outhereinafter or will become apparent as the description proceeds.

In the accompanying drawings, in which like reference numerals are usedto designate similar parts throughout, there is illustrated a suitablemechanical embodiment for the purpose of disclosing the invention. llhedrawings, however, are for the purpose of illustration only and are notto be taken as limiting or restricting the invention since it will beapparent to those skilled in the art that various changes in theillustrative construction may. be resorted to without in any wayexceeding the scope of the invention.

In the drawings:

Figure l. is a side elevational view of the chassis of a vehicleconstructed according to the invention, a portion being broken away tofurther illustrate the construction thereof;

Figure 2 is a top plan view or the vehicle chassis illustrated in Figure1;

Figure 3 is a side elevational view on an enlarged scale of theauxiliary engine transmission shown in Figures 1 and 2;

Figure i is an end elevational view of the aux= iliary enginetransmission shown in Figure 3;

Figure 5 is a top plan view of a valve actuated by the main enginetransmission and controlling the servo devices efiective to shift theauxiliary engine transmission;

between the main engine Figure 8 is an end elevational view of the valveshown in Figure 5 showing in end elevation a valve operating finger onan arm secured to and controlled by the shirt device of the main enginetransmission;

Figure 7 is a vertical sectional view of a portion of the valve talrenalong the line l-l 01 Figure 5 Figure 8 is a sectional view similar toFigure 7 showing a different operative position of the valve;

Figure 9 is a sectional view of the valve shown in Figure 6 taken alongthe line 9-23 of Figure 5;

Figure 1G is a sectional view similar to Figure 9 showing a difierentoperative position of the valve from that illustrated in. Figure 9;

Figur ii. is a vertical sectional view similar to Figure 9 showing adifferent operative position of tlse valve from those illustrated inFigures 9 and 1 Figure 12 is a plan view of mechanism for rendering theauxiliary engine clutch operative by the main clutch pedal when theauxiliary engine is operating;

Figure 13 is a sectional view on the line iii-53 of Figure 12;

Figure id is a diagrammatic'sectional view of an improved bralrearrangement; and

Figure 15 is a diagrammatic view of a suitable signing and ignitioncircuit for the auxiliary en- E e.

errlng to the drawings in details and particularly to Figures l and 2,the numeral as generally indicates a vehicle frame supported from frontand rear road engaging wheels, as indicated at 22 and Ed, byconventional springs, or other suspending means, not illustrated. IFrame 2t carriesa main engine 26, connected through a clutch 28, changespeed transmission 30, propeller shaft 32, two speed rear axle drivegear 34, diiferential 36 and rear axle 38 with the rear wheels 2d, andalso carries a booster engine 50 connected through a clutch Q2, changespeed transmission M, propeller shaft Q8, disengageable gear drive 48,differential 50 and front axle E52 with the dirigible front wheels 22.

The rear axle two speed drive 34 may be similar to that shown anddescribed in United States Patent No. 2,183,667 issued December 19, 1939to Lawrence R. Buckendale, and may be shifted by a servo device 32'actuated in one direction by a compression spring, not illustrated, andin the opposite direction by the pressure differential existing betweenthe main engine intake manifold and atmospheric pressure. The connectiond9 intake manifold and the servo device 32' may lead through a suitablemanually actuatable pneumatic valve 53,

shown in detail in copending application Serial No. 506,582, illedOctober 16, 1943, which valve may constitute a portion of theautomatic'apparatus which controls the starting and stopping of thebooster engine. As illustrated, the valve is interposed in the fluidconnection d9 between the main engine intake manifold and the rear axleclutch actuator 32' so that it functions to select the rear axle drivegear ratio. This valve is provided with a shaft extension 5? carrying aradial arm 59 connected with a switch 27 which is i. corporated in theauxiliary engine starting or in a manner illustrated in Figure 15 andfunctions to control the starting of the engine in a manner hereinafterdescribed.

Although the main engine and booster driving connections have commoncontrols, as will later appear. they are drivingly independent of eachother and the power output capacity of each engine is based on thetraction capacity of the axle to which it is connected. Thus, when mainengine is connected to dual wheel axle, and the booster engine isdrivingly con able to a single wheel front axle carrying so imately onehalf the load carried by the rear the booster engine might convenientlyhave power output capacity approximately one that of the main engine.The invention is not limited however to any specific ratio of the poweroutput capacities of the two engines, it b8176 portant only that thecapacities of the engi es shall correspond to the available tractiveeffort of the wheels driven thereby so that the wheels cannot beinjuriously slipped in normal operation.

The booster engine may have a starting device as indicated at 5%andsuitahle ignition apparent including coil 55, controlled by asuitable electric circuit indicated stile in Figure 1 anddiagrammatically illustrated in Figure 15, which will he hereinafterdescribed in detail. This control apparatus may be energized by abattery 58 through a suitable control switch to which may be man= uallyoperated.

The front axle diiierential Kill and the disengageable' drive gear 68may be similar to that shown in United States Patent No. 2,309,432, issued January 26, 19 .3, to ll. W. Alden for Motor vehicle, and the drivegear may be engaged by a servo device 32 having a spring which acts todisengage the gear and a connection 64 with the intake manifold of thebooster engine, whereby the pressure differential between the boosterengine manifold pressure and the atmospheric pressure Will overcome thisspring when the booster engine is operating and engage the gears therebycomdicated by the numeral I. The casing has a pleting the drive betweenthe booster engine pro- I peiler shalt 4i and the front driving axle 52.

Description of auxiliary engine transmission shift The booster enginetransmission 44 is shifted by a set 01! pneumatic servo devices 66, 68and 10, particularly illustrated in Figures 3 and 4, under the controlof the valve I2 particularly illustrated in Figures 5-11, inclusive.

The three servo units 66, 68 and II are similar in construction. whichconstruction is particularly illustrated in connection with the unitIII. This unit comprises a two part metal casing I4 enclosing atransverse diaphragm It and a coiled compression spring I8. Thediaphragm is connected at its center to an operating shaft 92 whichextends through an apertured bushing 80, and a fluid connection I02leads to the interior of the casing at the end thereoi opposite thebushing 80. With this arrangement the compression spring urges thediaphragm and operating rod in one direction d these are moved in theopposite direction when-the interior of the casing is subjected on theside connected with the fluid conduit to a fluid pr i e less thanatmospheric. Openings it are provided in the casing on the atmosphericpres sure side of the diaphragm.

e servo unit it, through its operating rod lit, the lever am it andshaft it, controls the low gear ratio of the auxiliary enginetransmission, the spring urging the mechanism to a neutral position andthe application of vacuum through the conduit as moving the diaphrouruout the shrine to engage the low speed gear. The intermediate and highspeed gear ratios are controlled by the units ill and lit through theiroperating shafts lit and 92', the lever arm 43 and the shalt in thisarrangement when there is no applica tion oi manifold vacuum to eitherof these units d it the spring in unit til forces the lever lid to theposition shown in full lines in Figure 3 in which the transmission is inits high speed gear ratio. if manifold vacuum is applied to the unit tilonly, the lever to will he tinned to the indicated neutral position inwhich looth intermediate and high speed gears are placed in neutral,coming to rest against the bottom of the slot in the rod iii. if vacuumis applied to both of the units til and lit the slot to will he moveddownwardly lay the unit it and the lever El i will he turned by the unittil to the indicated intermediate speed position. Application of vacuumto the unit tt is efiective to move lever so lrom direct drive to neutwhen further move ment is limited by the bottom of the slot in rod ti dalso to move lever so from its neutral to its intermediate speedposition when the stop constituted by the upper position of rod 82 is re'oved. Unit it moves the rod. 92 and slot Mi dowardlv to remove the stopat neutral for the lever til so that the intermediate speed may heengaged by the application 0t vacuum to fragment of which is shown inFigure 9 and inpair 0! parallel bores Ill and IIII within which areslidably mounted respective valve plungers H2 and I. Theseplungersproiect at one and outside of the casing and carry on theirprojecting ends respective gates or lugs III and III engageable byfinger I20 formed on the end of bracket arm I22 welded'or otherwisefirmly secured on gear shift lever Ill.

when the main transmission is in neutral, plunger Ill will occupy theposition in bore III illustrated in Figure 7 in which position port I24,connected with the atmosphere through the filter I28, is connectedthrough annular reduction I28 on the valve stem and port I with conduit88 leading to servo unit 66, thus permitting the spring in unit it tomaintain the auxiliary transmission low speed gear train in neutral.Plunger H2, at the same time. occupies the position in bore I08illustrated in Figure 9, in which position conduit in leading to servounit 60 is connected with the atmosphere through fllter I26, port I32,annular groove I34 on valve stem H2 and port I36 thus permitting thespring in unit N to urge lever 94! in an anticlockwise direction, asviewed in Figure 3, toward the third or direct speed drive of theauxiliar'y transmission. At the some time, however, conduit M2 leadingto servo unit it is connected through hole illll, elongated port ltd invalve stem N2, axial bore M2 in the valve stem, the end of bore it,birch channel Mt leading into the end of bore lot, hole lit and conduitlit with the interior of the intake mold of the booster engine. 4

if the loocster engine is operating, the pressure difiierential exertedon diaphragm ill will pull the diaphragm downwardly, as viewed in Figure3, until the end of rod 92 within the unit strikes abutmentlilllstopping rod 32 in a posi tion in which the upper end of slot toholds lever st in its neutral position in which neither the high norintermediate speed ratios of the can he engaged. It there no vacuum inthe booster ensure intake manifold, spg ill will move shaft 822 upwardlypetting lever lid to swine until the direct speed drive oi theainziliai'v transmission is eneased, which is the normal condition oithis trassinn'whell the booster engine is not operating. at the sametime the booster engine will he disengaged from its associated drivingaxle by servo unit (it. as descrihed above.

When the main trmission is moved to the low or creeper speed position,plunger 962 does not move out-oi its neutral position but plunger lit ismoved outwardly with respect to bore lid. ular groove lid however is ofsumcient length to keep conduit 83 connected with the atmosphere so thatthe low auxillary' mission speed remains in neutral and, ii the boosterengine is operating, the high and inter mediate speed gear trains alsoremain in neutral, so that the booster engine is not drivingly connectedwith its associated axle when the main tr =11 ssion is in low or creepergear ratio.

when the main trion is shifted to second speed plunger II2 remains inthe neutral position with the eflect described above, but plunger i I ismoved inwardl; relative to bore Ii. to the position particularlyillustrated in Figure 8 in which conduit II is connected through portI", hole I52, axial bore, Ill in plunger Ill, branch channel I, hole I"and conduit I with the booster engine intake mantranshicle through itslow speed drive gear ratio corresponding to the second speed drive gearratio of the main transmission.

It is thus seen that plunger lid has only two operative positions whichpositions are deter-- mined by engagement of spring pressed detent ltdwith one or the other of notches I58 and ledprovided in plunger lid.

If now the main engine transmission is shifted from its second to itsthird speed gear ratio, passing of shift lever HIE through neutral willcause finger ii to return plunger lit to its neutral position and engagein lug i it of plunger H2 and movement of the lever to place themain.trans mission in the third speed gear ratio will move plunger M2 tothe position particularly illustrated in Figure 10.

In the position particularly illustrated in Fi ure iii conduit 5% isconnected with the booster engine intake manifold through hole i36, portit! and bore. 562 while, at the same time, conduit W2 will be connectedwith the booster engine intake manifold through hole 39, elongated portMd and bore M2 through branch channel ltd, hole M6 and conduit I58. Withthis position of valve plunger M2, manifold vacuum will be applied toboth units 68 and it moving rod lit upwardly and rod 92 downwardly, asviewed in Figure 3, and swinging lever t l to the indicated intermediatespeed position.

When the gear shift lever is moved to place the main transmission in itshigh or direct speed drive, plunger H2 will be moved to the positionillustrated in Figure 11. In this position of the plunger conduit Hillis connected with the atmosphere through hole i361, annular groove ltd,hole E32 and filter Q26. At the same time, conduit i922 will beconnected with the atmosphere through hole lS B, annular groove M32,hole ltd and filter we thus connecting both of the units and lil withthe atmosphere and permitting the compression springs therein torespectively move rod tit downwardly and rod Q2 upwardly, thereby tiltinlever 9d to the indicated direct drive position for the auxiliarytransmission.

Return of the gear shift lever to neutral will place the plungers in thelocations shown in Figures 7 and 9 respectively and place all of theauxiliary transmission gear drives in neutral when the booster engine isoperating, as explained above.

' Plunger ill-thus has three positions in which it is steadied by springpressed detent I56 engaging in one or the other of notches 668, I16 andH2.

Description of auxiliary engine cluch control mechanism The main engineclutch 28 may be operated by a suitable foot pedal, not illustrated, inthe conventional manner. In order to obtain'operation of the boosterengine clutch 2, link We may be connected to the clutch pedal andextended rearwardly of the vehicle to a pivotal connection lit with thefree end of a lever I18 secured at, its opposite end to a torque shaft880 rotatably mounted in a suitable bracket I82 rigidly secured to thevehicle. Torque shaft W0 extends through bearings carried by bracket I82toward the booster engine clutch 22 and a second torque shaft ltd, whichoperates the booster engine clutch, extends into abutting relationshipwith the adjacent end of torque shaft i and is coaxial therewith. Abracket member H6 is clamped upon the end of shaft I85 and rotatablyreceives the end of shaft ldil and is provided with a bore 388 extendingtransversely of shaft ltd within which is a slidable plunger or drop pinlilo. Pin 699 is provided with an annular groove 5% intermediate itslength, and shaft H80 is provided with a notch ill-l, the groove andnotch being so arranged that, when the groove of the plunger is centeredover the shaft H80, the shaft may 20- tate freely in bracket H86 but,when the plunger is moved to bring a portion thereof beyond the annulargroove in line with shaft i863, the shaft will be locked relative tobracket H86 and rotational movements of shaft 580 will be transmitted toshaft i8 3 so that operation of the main engine clutch willsimultaneously operate the auxiliary engine clutch. This arrangementconstitutes a simple, automatically actuated drop pin construction foroperatively connecting the two clutches together when the booster engineis operating.

Plunger 89b is connected at one end to the center of diaphragm 69 3peripherally clamped in a housing i955 the interior of which isconnected through conduit 598 with the booster engine intake manifold.Normally plunger itlil is held in position to release the shaft iilil bycoiled compression spring 2%, but, when the booster engine is operating,the effect of the intake manifold vacuum overcomes the force of spring2M1 and moves plunger led into position to interlock shafts liifl andled.

Operation 07' the auxiliary engine transmission shifting mechanism andclutch control From the above description it will be apparent that, whenthe booster engine is not, operating, the auxiliary engine clutch willnot be operated and the auxiliary engine transmission will remain in itsdirect speed drive gear ratio, while the booster engine propeller shaftwill be drivingly disconnected from the associated driving axle. Whenthe booster engine is operating, the booster engine clutch will beconnected with the main engine clutch so that both clutches will beoperated simultaneously and the servo shifting means for the boosterengine transmission will be connected with the main engine transmissionin such a manner that whenever the main engine transmission is inneutral or in its lowest speed drive gear the booster enginetransmission will be in neutral, but, when the main engine transmissionis placed in either its second, third or fourth speed drive, the boosterengine transmission will be simultaneously placed in its correspondinglow, intermediate or high speed drive and the booster engine propellershaft will be drivingly connected with the associated driving axle.

Description 0] improved. brake installation addition to the conventionalwheel brakes of the vehicle but, in some installations, might besubstituted for the rear wheel brakes.

In this arrangement a brake drum 288 is mounted by a suitable splineconnection 282 on the power shaft 284 which projects from the rear axlehousing 88 andis connected with the main engine propeller shaft 32through a suitable universal joint. mounted on the housing and carries asuitable external brake band or shoe 288 moved into engagement with thedrum 288 by suitable conventional means, not illustrated.

With this arrangement the conventional gear reduction between the reardriving axle 88 and the shaft 222 through the ring and pinion gear andthrough the two speed drive gears can be used to advantage in reducingthe actual torque imposed on the brake so that the frictional resistanceof the brake is greatly multiplied as it is applied to the road wheels2% thus permitting a magnified braking eflort with a minimum of heatdissipated by the brake and with a break mechanism of reasonable sizeand weight.

Description of improved starting and ignition circuits for the auxiliaryengine A suitable starting and ignition circuit for the booster engineis diagrammatically illustrated in Figure 15. It is to be understood,however, that the invention is not limited to this particular circuitbut either a fully automatic circuit or a manual circuit may be utilizedif desired instead of the combined manual and automatic circuitillustrated.

In the circuit illustrated, the battery 58 is grounded at one side, asindicated at 282, and is connected at its opposite side to a starterswitch 228 closed by solenoid 288 and opened by spring 228. The switch204 when closed acts to connect the starter motor 54 directly with thebattery 88, the starter motor being suitably grounded to the vehicleframe as indicated by the ground lead 288. An electrical conductor 2B2leads from the live or ungrounded side of battery 58 to contact M8 sothat the main engine ignition circuit will be completed in either thebooster engine manual or automatic position of the switch.

One end of the booster engine starter solenoid 288 is connected with theground connection 226 through a switch, generally indicated at 228. Thisswitch may be of the low voltage 011 damped switch type and comprises,in general, acasing 238 within one end of which is mounted a fixedcontact member 232 insulated from the casing and connected with thesolenoid 288 by the conductor 234, and a movable contact 238electrically connected with the casing by a compression spring 238, thecasing being suitably grounded by the ground connection 228. An oilpressure conduit 248 leads from the output side of the auxiliary enginelubricating oil pump to a chamber in the casing 238 in which thecontacting ends or the members 232 and 238 are located, one end of thischamber being constituted by the end 01 the casing supporting thecontact member 232 and the other end being constituted by a par- Ananchor .plate 288 is rigidly.

tition 242' providing a bearing for the movable contact member 238. Aslight clearance is preferably provided between the member 238 and thebearing 242 so that a small quantity of oil can flow from the conduit248 out of the chamber and through a different part of the casing to theoil return conduit 244 in order to replace cold oil in the chamber withwarm oil from the engine to improve the operation of the switch. I!

it is desired to combine the maniiold pressure operated switch functionwith the oil pressure operated switch, the end of the member 238opposite the contact member 232 may be connected to a diaphragm 248 in apneumatic chamber 288 connected through a conduit 288 with the intakemanifold 282 of the boosterenglne 42. Otherwise a separate manifoldpressure switch may be provided, connected in series with the oilpressure controlled switch.

When the booster engine is not operating, the compression spring 228will move the member 238 into contact with the member 232 therebycompleting'the ground connection of the solenoid 228. As soon, however,as the auxiliary engirie starts, the partial vacuum in the manifold Theend of the starter switch solenoid 288 opposite to the end connected tothe switch 228 is connected through a conductor 284 with a terminal 258of the switch 88.

If manual operation of the booster engine is desired, the lever 288 01'the ignition switch 88 may be moved in the direction of the arrowlabelled manual which wlll'connect the contact 2M with the contact 288energizing the solenoid 288 to operate the starter 84 and this circuitwill be broken by the switch 228 as soon as the booster engine isstarted. At the same time the booster 'engine ignition circuit includingthe coil 88 will be energized from the terminal 288 through theconductor 288 and a suitable ground connection indicated at 288.

If automatic operation of the booster engine is desired, the lever 288will be moved in the direction of the arrow labelled automatic whichwill connect the terminal 288 with the terminal 282 which terminal isconnected through a conductor 288 with one contact oi a control unit288. This unit is connected through a pair of pneumatic conduits 288 and218 with the space ahead of and with the throat of a Venturi tubeinterposed between the main engine carburetor and the main engine intakemanifold, all as particularly illustrated and described in ouroo-pending application Serial No. 508,582, filed October 16, 1943. Fromanother terminal of control unit 288 a conductor 212 leads to thebattery line 212 so that, when the switch 88 connects the terminals 288with the terminal 282, the starting circuit and ignition circuit of theauxiliary engine is connected to the battery 88 through the automaticcontrol unit 288 which is so arranged that the booster engine will bestarted only when the speed and load factors of the main engine reachcertain predetermined conditions. With the automatic circuit inoperation the switch 228 will still act to disable the starter of thebooster engine and maintain the starter against operation as long as thebooster engine is operating, in the manner described. above.

Preferably a switch 21s is included in the conductor 26d and this switchmay be operated by valve 53 which controls the ratio selection of thetwo speed rear axle in a manner such that the switch is closed only whenthe rear axle of the vehicle is in its low speed ratio thus limitingautomatic operation of the auxiliary engine to those occasions when thelower speed ratio of the two speed rear axle is being utilized.

This switch may be provided with a manually operated lockout of someform known to the art so that, when desired, the main engine may beoperated and the booster engine maintained inoperative by operatlng themain engine on the automatic controls and maintaining the switch 214open. If desired, a second switch MS may be installed between theconductors Eli? and 25% in order that the auxiliary engine may bemanually operated without use of the master ignition switch 60. Thiswould permit operation of the auxiliary engine for testing and otherpurposes without the necessity of completing the ignition circuit of themain engine.

The invention may be embodied in other specific forms without departingfrom the spirit or essential characteristics thereof. The presentembodiment is therefore to be considered in all respects as illustrativeand not restrictive, the scope of the invention being indicated by theappended claims rather than by the foregoing description, and allchanges which come within the meaning and range of equivalency of theclaims are therefore intended to be embraced therein.

What is claimed and desired to be United States Letters Patent is:

1. In a vehicle having two independent drive secured by axles, a mainengine drivingly connectible with one of said axles; a booster enginedrivingly connectible with the other of said axles; a driving connectionincluding manually controlled elements between said main engine and saidone axle; a controllable driving connection between said booster engineand said other axle; and means rendered operative by operation of saidbooster engine to enable said manually controlled elements to controlthe driving connection between said booster engine and said other axle.

2. In a heavy duty automotive vehicle having a rear drive axle and afront steering drive axle; a main engine carried by said vehicle andhaving a power output capacity sumcient to propel said vehicle undernormal driving conditions; drive means including a transmission havingfour for- Ward'speeds drivingly connecting said main engine with saidsaid rear axle; an auxiliary engine having a power output capacityconsistent with the normal power absorbing tractive capacity of thevehicle front wheels also carried by said vehicle; and drive meansindependent of said main engine drive means operative to drlvinglyconnect said auxiliary engine with said front axle, said auxiliaryengine drive means having only three speeds corresponding to the second,third and fourth forward speeds of said main engine transmission tofurther avoid undue load and strains on the mechanism of said frontdrive steering axle.

' 3. In a dual engine vehicle, a rear two speed drive axle driven by oneof said engines, a front steer drive axle driven by the other of saidengines, and control means selectively operable to power said vehicleonly by said one engine driving said two speed axle at its higher speed,only by said one engine driving said two speed axle at its lower speed,or by both of said engines driving their associated axles with said oneengine driving the two speed axle at its lower speed.

4. In a vehicle, a multi-speed drive rear axle, an engine connected todrive said axle, a front steer drive axle, a second engine connected todrive said front axle, means operable to selectively shift the gearratio of said multi-speed axle; and means having an interlock with saidfirst mentioned means operative to control opera tion of said secondengine.

5. In a vehicle, a two speed drive axle; means for selecting the drivespeed of said axle; a second drive axle having a single drive speedcorresponding to the lower speed of said two speed drive axle; means fordriving said axles simultaneously; and means disabling said single speedaxle drive when the higher speed of said two speed axle is selected.

6. In a vehicle, a multi-speed drive axle, means for selecting the drivespeed of said axle; a second drive axle having a single speedcorresponding to one speed of said multi-speed drive axle; individualpower plants for driving said axles; means controlling operation of saidsecond drive axle and its associated power plant so as to drive saidsecond axle only when said multi-speed axle is driven at said one speed;and means renderin said controlling means inoperative when saidmulti-speed axle is being driven at a speed different from that of saidsecond drive axle.

7. In a vehicle, a two speed drive axle for normally driving thevehicle; means for selecting the drive speed of said axle; a singlespeed drive axle, having a drive speed corresponding to the lower speedof said two speed drive axle, for augmentin the two speed drive axleunder predetermined abnormal driving conditions; means-for independentlydriving said axles; and control means for starting the driving means forsaid single speed axle and selecting said lower speed of said two speeddrive axle and subsequently connecting said single speed axle to itsdriving means.

8. In a vehicle, a two speed rear drive axle; a front steer drive axlehaving a speed ratio corresponding to the lower speed of said two speeddrive axle; individual power plants operabiy associated with therespective axles; control means for selectively starting the power plantassociated with said front axle and for coupling it thereto; and meansresponsive to operation of the power plant driving said two speed driveaxle for rendering said controlling means so operative only when saidmulti-speed axle is being driven at its lower speed.

9. In a vehicle, a multl-speed rear drive axle having at least two drivegear ratios; a first engine drivingly connectable with said axle;manually controlled engine actuated means operatlvely associated withsaid axle for selecting any particular one of the available axle gearratios for the drive connection; a front steer drive axle; a secondengine drivingly connectable with said front axle; control means forrendering said second engine operative or inoperativeto drive said frontaxle; and means operatively associated with said gear ratio selectingmeans and said control means operative upon the selection" of apredetermined multi-speed axle gear ratio to render said control meanseffective to establish operativeness of said second engine to drive saidfront axle and operative at all other times to render said control meansineffective to establish said operativeness of said second engine.

10. A vehicle as defined in claim 9, including a clutch in said frontaxle; and means actuated by said second engine eifective to engage saidclutch when said engine is operating and disengage said clutch when saidengine is not operating. I

11. In a vehicle, a multi-speeddrive axle having at least two drive gearratios; a first engine drivingly connectable with said axle; manuallycontrolled engine actuated means operatively associated with saidaxlefor selecting any particular one of the available axle gear ratiosfor the drive connection; a single speed axle; a second engine drivinglyconnectable with said sin le speed ax e: control means forre deri saidsecond engine operative or inoperative to drive said single speed axle;and means operatively associated with said second engine having aneffectiveness conditioned on the operation of drivingly connectable withsaid axle; manually controlled engine actuated means operativelyassociated with said axle for selecting any particular one of theavailable axle gear ratios for said driving connection; a single speeddrive axle; a second engine drivingly connectable with said single speedaxle; means operatively associated with said single speed axle actuatedby said second engine to establish a driving connection between saidsecond engine and said single speed axle; and means operable upon theselection of a predetermined multi-speed axle gear ratio to render saidsecond engine effective to actuate said drive establishing means. v

13. In a heavy duty vehicle having a rear drive axle arrangement and afront steer drive axle: a main engine having a power output capacitysufllcient to propel the vehicle under normal driving conditionsdrivingly connected with said rear axle arrangement; an auxiliary enginehaving a power output capacity based on the load carried by said frontaxle and less than said main engine power output capacity connectablewith said front axle by means drivingly independent of said main axledrive; a multi-speed drive gear mechanism in said rear axle having twodrive ratios and said front axle comprising a gear mechanism having adrive ratio corresponding to one of said two drive ratios; and means forcontrolling said engines and their respective drive connections toprovide operation of said main engine alone or simultaneous operationsof both engines, said means including shift mechanism mechanismindependent of said main engine drive; said front axle including adouble reduction drive gear, and said rear axle being provided with atwo speed double reduction drive gear to provide additional gear ratiosfor said main engine drive; means for selecting the drive speed of saidrear axle, and means controlled by said selecting means for establishinga drive connection between said auxiliary engine and said front axleonly when said rear axle is driven at its lower drive speed and whensaid auxiliary engine is operating.

15. In a vehicle, a two speed rear axle and means for selecting itsdrive speed ratio, a front drive axle, a clutch in said front axle,individual engines connected to drive the respective axles, actuatormeans normally maintaining said clutch disengaged, means controlled bysaid selecting drive axle having speed ratio selector means and a frontsteer drive axle connected to said chassis; shiftable clutch means insaid front drive axle; individual power means for driving said axles;starting means for said power means driving the front axle controlled bysaid speed ratio selector means; and means for actuating said clutchmeans operative to permit engagement of said clutch means only when apredetermined speed ratio of said multi-speed drive axle is selected andthe power means for driving said front axle is operating.

1'7. In a vehicle, a multi-speed drive axle having speed ratio selectingmeans, a second drive axle having a speed ratio corresponding to a speedratio of said multi-speed axle, individual power plants connected todrive the respective axles, means controlling operation of said seconddrive axle and its associated power plant, and means rendering saidcontrolling means operative to initiate operation, of the power plantconnected with said second drive axle only when said multispeed axle isbeing driven at a speed ratio corresponding to said speed ratio of saidsecond drive axle.

18. In a vehicle, a multi-speed rear axle, drive speed ratio selectingmeans for said axle, a main engine connected to drive said axle, a frontdrive axle having a speed ratio corresponding to a speed ratio of saidrear'axle, an auxiliary engine connected to drive said front axle,starting control means for said auxiliary engine, and means respeedratio selecting means for said axle, a main engine connected to drivesaid axle, a second drive axle having a speed ratio corresponding to aspeed ratio of said multi-speed axle, an auxiliary engine connected todrive said second axle, starting control means for said auxiliaryengine, and

8 assures manual control means for said second speed ratio selectingmeans operative to condition said starting control means to precludestarting of said auxiliary engine except upon selection of a speed ratiofor said multi-speed axle corresponding to 5 said speed ratio of saidsecond axle. v

20. In a vehicle having a multi-speed rear axle drive connected to amain engine and a steer drive front axle drive connected to an auxiliaryengine, speed selector means for said multi-speed l0 operation of saidmain engine for operating the other of said switches.

. WALTER F. ROCKWELL.

BEVERLY W. msn.

